1. Field of the Invention
An apparatus, method, system for communicating with a counterpart communication apparatus via a network using more than one communication procedure or protocol. The communication procedure or protocol is selected based on the presence information or location information of a firewall on the network.
2. Description of the Related Art
Today, a large number of apparatuses communicate to one another via a network using a variety of communication procedures or protocols.
For example, in a communication system shown in FIG. 1, a first communication apparatus A and a second communication apparatus B are connected via a network N, such as the Internet. When the first communication apparatus A functions as a client, the first communication apparatus A sends a communication request to the second communication apparatus B. The communication request contains an operation request asking the second communication apparatus B to perform a requested service. In response, the second communication apparatus B, which functions as a server, sends a communication response to the first communication apparatus A. The communication response contains an operation response indicating the result obtained by performing the requested service. Alternatively, when the second communication apparatus B functions as a client, the second communication apparatus B sends the communication request or the operation request to the first communication apparatus A. In response, the first communication apparatus A, which functions as a server, sends the communication response or the operation response to the second communication apparatus B.
The communication system of FIG. 1 may be additionally provided with a firewall F, for example, as illustrated in FIG. 2. The first communication apparatus A is provided outside of a local network including the second communication apparatus B and the firewall F. With this network structure, communication between the first communication apparatus A and the second communication apparatus B may not be established unless the second communication apparatus B allows the first communication apparatus A to access the second communication apparatus B.
For example, in order to send an operation request from the first communication apparatus A to the second communication apparatus B, the first communication apparatus A waits until it receives a communication request from the second communication apparatus B. Upon receiving the communication request from the second communication apparatus B, the first communication apparatus A may request the second communication apparatus B to perform a requested service by sending the operation request to the second communication apparatus B. Upon receiving the operation request, the second communication apparatus B may send an operation response to the first communication apparatus A, which contains the result obtained by performing the requested service.
In another example, in order to send an operation request from the second communication apparatus B to the first communication apparatus A, the second communication apparatus B may send a communication request or an operation request in a substantially similar manner as described above referring to FIG. 1. However, the second communication apparatus B may preferably use a protocol, which is suitable to the firewall.
As described above referring to FIGS. 1 and 2, the first communication apparatus A and the second communication apparatus B communicate differently depending on whether the firewall is provided between the first communication apparatus A and the second communication apparatus B, or whether the firewall is located inside or outside the local network. Accordingly, the structure of the first communication apparatus A or the second communication apparatus B may need to be changed depending on the presence or location of the firewall.